Some time ago, I posted that DPMS screen screen-shutoff mysteriously stopped working, and later just as mysteriously started working again. I've finally figured out the culprit by accident... dosbox. There are various MS-DOS game archives on the internet with over 4 decades of very entertaining games. I use "dosbox" to run old stuff.
If I'm in the middle of a game "level" and want to continue it later, I can window-ize dosbox, {ALT}{PAUSE} to toggle execution off, and then minimize the window. Later on, I can bring up the window, {ALT}{PAUSE} to toggle execution on, and maximize to fullscreen "text mode". The only problem is that DPMS screen powersaving does not work while dosbox is running, or even suspended with {ALT}{PAUSE}. This is not specific to any one game. Even a dosbox window at a command prompt disables DPMS screen-off. I've compared the output of "xset -q" with and without dosbox running, and there's no difference. Has anyone else noticed this, or is it something weird with my config? -- There are 2 types of people in this world 1) Those who can extrapolate from incomplete data